Pointed earthed conductors are put on tall buildings to

Pointed earthed conductors (called lightning conductors) are put no tall buildings, when charge clouds pass nearlby high buildings, they induce opposite charges on pointed ends, which due to action of points send similarly charged ions which may either neutralize the charged bottom cloud, thereby preventing the discharge. If at all the discharge occurs, it will occur through the conducting strip which may allow charge to pass through it to earth.